The events that occur inside the tooth during caries formation will be studied experimentally. Teeth will be sectioned and very small wells will be drilled into the enamel parallel to the surface and at various distances from the surface. Some of the wells will be drilled into sections containing natural or artifical incipient lesions. The sections will then be placed into carciogenic solutions and the compositions of the solutions in the wells will be measured as functions of (1) time, (2) composition of the external solution, (3) perm-selective properties of the membrane comprising the enamel surface, and (4) distance of the well from the surface. The objectives are to establish the relative importance of the various thermodynamic and kinetic phenomena in the caries process and to identify those events in the mechanism that might be altered to prevent caries. The techniques to be used in the above demineralization studies will also be applied to remineralization in an effort to develop effective procedures for repair of white spots.